This application claims the benefit of Japanese patent application No. 10-329339, filed Nov. 19, 1998, which is hereby incorporated by reference.
1. Field of the Invention
The present invention relates to an AC-driven surface discharge plasma display panel (AC-PDP), and more particularly, to an AC-PDP having a lower discharge start voltage.
2. Description of the Related Art
A plasma display panel (PDP) typically has a large size and thin color display. FIG. 1 is a cross-sectional view of an AC-driven surface discharge plasma display panel (AC-PDP). The structure and operation of this AC-PDP will be described next.
As shown in FIG. 1, the AC-PDP includes a glass substrate 1 located on the front side, and has a pair of discharge-sustaining electrodes 2, 2 for each display line. These electrodes maintain the electric discharge and are formed by a film having a thickness of several hundred nanometers. A dielectric layer 3 covers the electrodes 2 and is made of a film having a thickness of 20 to 30 xcexcm. A protective layer 4, which is made of MgO, covers the dielectric layer 3.
Each electrode 2 includes a plurality of transparent electrodes 2a, which are made of a wide transparent conductive film, and narrow metal auxiliary electrodes 2b to complement the conductivity of the transparent electrodes 2a. As a result, the metal auxiliary electrodes 2b are required to have a low resistance and are made of a metal film, such as aluminum or the like.
Specifically, the dielectric layer 3 is formed by first applying a low-melting point glass paste, which includes lead oxide (PbO), to the electrodes 2 and then, baking the paste.
Another glass substrate 5 is located on the rear side of the AC-PDP, as shown in FIG. 1. A plurality of electrodes 6 are formed as addressing electrodes and extend parallel to each other. Ribs, which are not shown in FIG. 1, are also formed between the successive electrodes 6. A phosphor layer 7 is formed such that it covers the top surfaces of the electrodes 6 and the side surfaces of the ribs.
In this AC-PDP, the glass substrates 1 and 5 are spaced from each other such that the electrodes 2 on the glass substrate 1 face and extend perpendicularly with respect to the electrodes 6 on the glass substrate 5. As a result, a discharge space 8 is formed between the glass substrates when the outer periphery is sealed.
The ribs formed between the electrodes 6 partition the discharge space 8 into discharge cells along the direction in which the discharge-sustaining electrodes 2 extend. That is, the ribs partition the discharge space 8 into discharge cells in the direction of the display lines. The ribs also determine the gaps between the cells in the discharge space 8. After sealing the glass substrates 1 and 5, the discharge space 8 is evacuated, and then, rare gases are sealed in the space.
In this way, the AC-PDP of FIG. 1 has plural discharge cells. Furthermore, pixel cells are formed around the intersections of the electrodes 2 on the glass substrate 1 and the electrodes 6 on the glass substrate 5. Thus, an image can be displayed using this AC-PDP.
An operation that causes the discharge cells of this AC-PDP to emit light will be explained now. First, a discharge start voltage, which is a given voltage, is applied between the pair of discharge-sustaining electrodes 2 to produce electric discharge. As a result, wall charge is created. Then, a selection-eliminating pulse is applied to the addressing electrodes 6 corresponding to discharge cells that are not necessary for the display. In this manner, the wall charge on the dielectric layer 3 is eliminated.
Next, a sustaining pulse is applied to the electrode pair 2, 2. As a result, the electric discharge is maintained in the discharge cells whose wall charge was not removed. This sustained electric discharge emits ultraviolet radiation, which excites the phosphor layer 7, and as a result, light is emitted. In this AC-PDP, the protective layer 4 enhances the efficiency of the second electron emission and lowers the discharge start voltage.
The phosphor layer 7 provides a high-brightness display in an AC-PDP, such as the one described above. Moreover, the phosphor layer does not deteriorate and has a long life because it does not directly undergo an ion impact during discharge.
In an AC-PDP, such as the one described above, the discharge start voltage can be lowered by reducing the thickness of the dielectric layer 3. However, reducing the thickness causes an increase in the current density, which decreases the emission efficiency of the AC-PDP, shortens the life of the protective layer 4, and increases line or electrode breaks.
The amount of discharge current flowing through each discharge cell can be reduced by partially narrowing the transparent electrodes 2a that are opposite to each other within each discharge cell. However, this does not decrease the current density.
Accordingly, the present invention is directed to an AC-driven surface discharge plasma display panel (AC-PDP) that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide an AC-PDP having a lower discharge start voltage and a thinner dielectric layer, as compared to the AC-PDP of FIG. 1, by preventing an increase in the current density and without decreasing the emission efficiency, shortening the life of the protective layer 4, or increasing line or electrode breaks. That is, the AC-PDP may alleviate a decrease in the emission efficiency by preventing increases in the current density.
Additional features and advantages of the invention will be set forth in the description which follows, and will be apparent from the description, or may be learned by practice of the invention. The objects and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
In a first aspect and to achieve these and other advantages in accordance with the purpose of the invention, as embodied and broadly described herein, an AC-driven surface discharge plasma display panel (AC-PDP) includes a pair of substrates that face each other and define a discharge space therebetween, a pair of electrodes for each display line formed on an inner surface of one of the two substrates such that the electrodes face each other and define a discharge gap therebetween, wherein each of the electrodes has minute openings, and a dielectric layer covering the electrodes.
In another aspect, the present invention provides an AC-PDP having, in addition to the features of the AC-PDP of the first aspect, electrodes with minute openings such that the minute openings preferably have diameters smaller than the thickness of the dielectric film.
In a third aspect, the present invention provides an AC-PDP including, in addition to the features of the AC-PDP of the first aspect, electrodes that include transparent electrodes and metal electrodes. The metal electrodes are formed on the transparent electrodes and are spaced from the discharge gap. The minute openings are formed on the transparent electrodes.
In a fourth aspect, the present invention provides an AC-PDP including, in addition to the features of the AC-PDP of the third aspect, transparent electrodes that have protrusions located on opposite sides of the discharge gap in each discharge cell.
In a fifth aspect, the present invention provides an AC-driven surface discharge plasma display panel including first and second substrates that face each other and define a discharge space therebetween, discharge-sustaining electrodes formed on the first substrate, wherein the discharge-sustaining electrodes have minute openings, a first dielectric layer covering the discharge-sustaining electrodes, and addressing electrodes and ribs formed on the second substrate.
In the AC-PDP of the present invention, each of the transparent electrodes in a pair are located on opposite sides of a discharge gap for each display line. Since these transparent electrodes have plural minute openings, the area of transparent electrode in each discharge cell is smaller than the area of a transparent electrode without such openings. Therefore, the amount of discharge current per discharge cell, which is produced by the operating voltage applied to the electrodes, decreases.
Furthermore, by setting the diameter of the minute openings in the electrodes to be smaller than the thickness of the dielectric layer, the average density of the electric force lines on the surface of the dielectric layer can be decreased. The current density in the discharge space can be also reduced. Consequently, if the dielectric layer of the AC-PDP is made thinner and the operating voltage is lowered, the current density does not increase. Accordingly, the decrease in the emission efficiency of the AC-PDP can be circumvented. Additionally, the decrease in the life of the protective layer and line or electrode breaks can also be suppressed.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.